Out of coincidence to the recent Wet Sumping message, I have had my own surprising episode of a very wet sump start today. I had left my newly restored M7 for about 2 weeks (I have been very busy and not had the chance to ride it). It was left with a pretty hot oil tank full of 20W-50 oil. Starting it today, I left it to tick-over and was amazed (horrified) that about 1 pint (500ml) pumped out of the breather pipe onto the ground this amount of course doesn't include what the scavenge pump is returning to the tank so total amount must have been something like 600ml. Having owned other Norton twins before I have never known so much oil to drain down over such a short period. So I searched for this topic on this site and found 36 pages on this topic. To my relief there were examples of much worse examples compared to my one. So here is what this message is about.
It would be nice to know what is the average amount of oil that Dominators drain into the sump over a unit time. This would enable owners to judge if their engines was doing what they all do or is their engine much worse or better than average. Unfortunately the oil type makes a difference but generally speaking it going to be 20W-50 or 40 or 50 straight?
So to start the list:
My engine lost 600ml in 2 weeks (20w-50)
It would be nice to be able to get a list made from the reports of other owners and in this way we could get the average for the Heavy Twin engine (including Commandos and engines with a new oil pump fitted)
Hopefully enough details could be compared to get a reasonable average to either put owners mind at ease or alert them that their engine is wet sumping way too much.
Les
PS How to know the quantity?
Well my one pumped it out of the breather, but one could check the level in the tank before starting and then compare the height after the engine scavenge was seen to return to a spasmodic spurting from the initial continuous return flow and do a reasonable quantification.
Hi Michael...It would be t…
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+1 on Les, its the smalles…
+1 on Les, its the smallest clearance that counts and that's in the pump.
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In winter, because of the…
In winter, because of the low temperature, (unless you store your bike in a heated garage), the oil will quite probablybe slower to make it down to the crankcase. Perhaps aheavier grade of oil in the summer might be an answer. I certainly notice the difference between summer and winterwet-sumping withmy 77.I don't think that there is a real answer to the original question. No two pumps are the same and asthe oil gets older it (and I may be wrong here) will tend to pass byworn stationary pump gears quicker. There are surelytoo many factors to be able to come up with an answer that can be of much use.
Of course, one question I tend to fret over is, do I pour the oil that I have just drained from the crankcase straight back into the oil tank? I've been known to chuck it, or sometimes when there is a lot, I leave it to settle so that anything heavier than the oil sinks to the bottom, before I carefully put it back into the tank minus the last few dregs. I also worry about the cleanliness of the vessel I drain the oil into and any grot that drops off the bottom of the engine while I'm removing the drain plug.
Fresh oil gives so muchpeace of mind.
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See my advice Kevin. Using…
See my advice Kevin. Using a kitchen Pyrex jug to measure the drain-off then replace that with fresh oil to give e partial change. In a different but slightly similar vein - if you have a car radiator leak, always top it up with fresh anti-freeze coolant, not plain water.
Previously Kevin Feltoe wrote:
In winter, because of the low temperature, (unless you store your bike in a heated garage), the oil will quite probablybe slower to make it down to the crankcase. Perhaps aheavier grade of oil in the summer might be an answer. I certainly notice the difference between summer and winterwet-sumping withmy 77.I don't think that there is a real answer to the original question. No two pumps are the same and asthe oil gets older it (and I may be wrong here) will tend to pass byworn stationary pump gears quicker. There are surelytoo many factors to be able to come up with an answer that can be of much use.
Of course, one question I tend to fret over is, do I pour the oil that I have just drained from the crankcase straight back into the oil tank? I've been known to chuck it, or sometimes when there is a lot, I leave it to settle so that anything heavier than the oil sinks to the bottom, before I carefully put it back into the tank minus the last few dregs. I also worry about the cleanliness of the vessel I drain the oil into and any grot that drops off the bottom of the engine while I'm removing the drain plug.
Fresh oil gives so muchpeace of mind.
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Hi Michael...It would be the same...the controlling factor is the the amount that squeezes past the pump gears. The restriction of the plain big-ends does not equate to much. The clearance gap is about a thou but this is over the entire circumference of the big end edges...so we have about 5" x 2 (both sides) x2 (two big ends)....equals a massive 20 inch long gap of 1/2 thou (half max clearance). This will be far in excess of the clearance through the pump...*.The only time the big ends (roller or plain) would control the drain rate is if the pump was extremely worn to a point of being near useless, then the plain bearings would indeed pass less oil than the open roller.
* One might see it though that the plain journal feed holes are quite small (4mm?) and the clearance is only 1/2 -1 thou at this point, but since the flow to the hole is so slow and the remaining area it feeds into within the big end bearing is so large (as shown) oil can seep out more quickly than the drip feed rate from the pump and represents no restriction, unless the flow becomes substantial....
Les